Mallory distributor sheared my oil pump drive

[Zed Head]

I might have this backwards, and it doesn't help that the picture of the end of the dist. drive shaft is upside down but isn't the twist backwards for the scenario where the distributor stops and the pump keeps turning? Shaft turning counterclockwise, broken end pointed up. It looks more like the pump stopped and the distributor kept going.

Maybe I'm looking at the wrong end of the shaft, or just thinking backward. I haven't actually had one out.

Is it possible that the twist is old damage that finally fatigued and broke?

[steve91tt]

The twist direction is what you would expect if you held the top of the distributor end stationary and twisted the shaft counter clockwise (looking down from the distributor end).

When I first removed the distributor from the car it was difficult to turn. I thought the rotor was bound up or the bearings had seized. After removing the broken pieces it now turns easily. I assumed it was the broken parts jamming the shaft against the body of the distributor but as you say, this could be a red herring.

I see no evidence that the drive gear is spinning on the shaft. The entire shaft looks to be in very good shape except for the distributor tang.

I love a good mystery.

[Zed Head]

Thanks for the reply. Maybe my brain is stuck, hopefully it will unstick later if so, but the picture of the shaft and the broken piece in your first post shows a counterclockwise twist. The distributor has two tabs that fit around the one center piece at the end of the oil pump drive shaft. That piece sticks up and it's twisted counterclockwise,looking down on it as it would be in the engine. The only way to do that is if the distributor shaft is twisting ahead of the oil pump shaft. But the oil pump shaft is the driver not the driven. If you held the distributor shaft in place, put the car in gear and rolled it backward you could get the same twist.

Sorry if I'm not getting it. I enjoy looking at broken machines too.

[steve91tt]

Here is a photo of the shaft with the broken piece balancing on top. This photo was taken as it would be in the engine looking down at the distributor end.

The shaft turns counter clockwise when the engine is running. I may be wrong but it appears to me that this is the twist I would expect if you held the top of the shaft as it was driven counter clockwise from beneath.

[Zed Head]

Thanks, that clears it up for me. I was looking at it as attached at one of the long ends, not laid down. My perspective was off, if I had seen one out of the engine before I would have known the tab wasn't that long.

Kind of surprised that Mallory didn't show more interest since it looks like a failure of their product. Maybe you were talking to the wrong guy.

[zKars]

Now I feel really silly.:paranoid: Talk about assuming something and making the facts fit.. Its your dizzy jamming for sure.... Another lesson in humility...

[240260280z]

These marks are interesting